This invention relates to a mobile station for use in a radio frequency communication system, such as a mobile telephone system and, in particular, to a mobile station with a position display function known in the art. The mobile station may be a portable telephone set although description will be mainly directed to an automobile telephone set.
A conventional mobile telephone system has a communication service area and comprises a plurality of base stations and a plurality of mobile telephone sets. The base stations are fixedly placed at different positions in the communication service area and are assigned with area numbers which will be called station numbers, respectively. Each of the base stations periodically transmits a particular signal representative of one of the assigned station numbers.
Each of the telephone sets is carried on movable bodies, such as an automobiles. When the movable bodies are in the communication service area, the telephone sets can communicate with a selected base station which is selected from the base stations in the manner known in the art.
Each of the telephone sets includes a display unit for displaying a display datum. After receiving the particular signal, each of the telephone sets makes the display unit display the assigned station number as the display datum.
With the mobile telephone system, a user of each of the telephone sets can recognize his current position with reference to the display unit if he has full knowledge of correspondence between each base station and each station number. This is because the assigned station number is displayed on the display unit.
However, if the user does not have such knowledge, he can not immediately recognize an actual position from the assigned station number that is displayed on the display unit.